Skip to main content

Lead

Lead paint is a scary topic, especially in Massachusetts where a lot of the housing is old. Lead paint is also a complex topic. Because the effects of lead paint on children and adults are dire and since many children have suffered permanent disability because of exposure to lead paint, state and federal governments take a very proactive and cautious stance regarding lead paint. The authoritative sources are your state and federal websites dedicated to lead paint issues (some links are below).
Apparently lead was added to paint because it enhanced its longevity and was government sanctioned. This same website states that the dangers of lead paint began to be realized in the 30s and 40s and in 1955 paints that were to be used in home interiors were restricted to less than 1% by weight of lead. Lead paint was also expensive and used mostly for living rooms and window sills and other locations where durability and quality were important.
From the EPA and state materials (which, again, are the materials you should refer to) it seems that the biggest risk is from chipping and peeling paint which can be eaten by children (they like the sweet taste) and dust from lead paint released from windows and door jambs. If paint is in good condition it is of lower risk and can be painted over and encapsulated as far as I could understand. Again, this is a complex, thorny topic with the health of children at stake, so even though it takes time, please go through the official documentation.
A common question is trying to judge the risk of lead paint based on the age of the house. The most common cut-off is 1978. Houses built before 1978 are assumed to have lead paint and there are some rules that govern the purchase and sale of such houses. Before 1955 paints contained as much as 50% by weight of lead. This was reduced to 1% by weight in 1971 (by the Feds) and then, since 1977, the limit is 0.06% by weight. Massachusetts uses 1950 as a criterion for 'old' houses as far as lead goes. This EPA page has a rough graph showing the percentage of homes having lead paint by year of construction.
Resources:
Labels:

Comments

Post a Comment

Popular posts from this blog

A note on Python's __exit__() and errors

Python's context managers are a very neat way of handling code that needs a teardown once you are done. Python objects have do have a destructor method ( __del__ ) called right before the last instance of the object is about to be destroyed. You can do a teardown there. However there is a lot of fine print to the __del__ method. A cleaner way of doing tear-downs is through Python's context manager , manifested as the with keyword. class CrushMe: def __init__(self): self.f = open('test.txt', 'w') def foo(self, a, b): self.f.write(str(a - b)) def __enter__(self): return self def __exit__(self, exc_type, exc_val, exc_tb): self.f.close() return True with CrushMe() as c: c.foo(2, 3) One thing that is important, and that got me just now, is error handling. I made the mistake of ignoring all those 'junk' arguments ( exc_type, exc_val, exc_tb ). I just skimmed the docs and what popped out is that you need to return True or...
Post a Comment
Read more

Store numpy arrays in sqlite

Use numpy.getbuffer (or sqlite3.Binary ) in combination with numpy.frombuffer to lug numpy data in and out of the sqlite3 database: import sqlite3, numpy r1d = numpy.random.randn(10) con = sqlite3.connect(':memory:') con.execute("CREATE TABLE eye(id INTEGER PRIMARY KEY, desc TEXT, data BLOB)") con.execute("INSERT INTO eye(desc,data) VALUES(?,?)", ("1d", sqlite3.Binary(r1d))) con.execute("INSERT INTO eye(desc,data) VALUES(?,?)", ("1d", numpy.getbuffer(r1d))) res = con.execute("SELECT * FROM eye").fetchall() con.close() #res -> #[(1, u'1d', <read-write buffer ptr 0x10371b220, size 80 at 0x10371b1e0>), # (2, u'1d', <read-write buffer ptr 0x10371b190, size 80 at 0x10371b150>)] print r1d - numpy.frombuffer(res[0][2]) #->[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.] print r1d - numpy.frombuffer(res[1][2]) #->[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.] Note that for work where data ty...
Post a Comment
Read more